Kiwy drawing

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.image import Image
from kivy.uix.button import Button
from kivy.uix.widget import Widget
from kivy.graphics import Color, Line
from kivy.core.window import Window

class DrawLayer(Widget):
def init(self, **kwargs):
super().init(**kwargs)
self.strokes = [] # store all drawn lines
self.current_color = (1, 0, 0) # default red
self.current_width = 2 # default thickness
self.drawing_enabled = False # drawing toggle


def on_touch_down(self, touch):
    if not self.drawing_enabled:
        return False

    with self.canvas:
        Color(*self.current_color)
        new_line = Line(points=[touch.x, touch.y], width=self.current_width)
        self.strokes.append(new_line)
    return True

def on_touch_move(self, touch):
    if self.strokes and self.drawing_enabled:
        self.strokes[-1].points += [touch.x, touch.y]

# ==========================
# UNDO LAST LINE
# ==========================
def undo(self):
    if self.strokes:
        last = self.strokes.pop()
        self.canvas.remove(last)

# ==========================
# CHANGE COLOR
# ==========================
def set_color(self, color_tuple):
    self.current_color = color_tuple

# ==========================
# CHANGE LINE WIDTH
# ==========================
def set_thickness(self, value):
    self.current_width = value
class EditorUI(BoxLayout):
def init(self, **kwargs):
super().init(orientation="vertical", **kwargs)


    # Background image
    self.img = Image(source="graph.png", allow_stretch=True)
    self.add_widget(self.img)

    # Drawing layer above image
    self.draw = DrawLayer()
    self.add_widget(self.draw)

    # Toolbar
    toolbar = BoxLayout(size_hint_y=0.15)

    toolbar.add_widget(Button(text="Draw On", on_press=self.toggle_draw))
    toolbar.add_widget(Button(text="Red", on_press=lambda x: self.draw.set_color((1,0,0))))
    toolbar.add_widget(Button(text="Blue", on_press=lambda x: self.draw.set_color((0,0,1))))
    toolbar.add_widget(Button(text="Green", on_press=lambda x: self.draw.set_color((0,1,0))))

    toolbar.add_widget(Button(text="Thin", on_press=lambda x: self.draw.set_thickness(2)))
    toolbar.add_widget(Button(text="Thick", on_press=lambda x: self.draw.set_thickness(6)))

    toolbar.add_widget(Button(text="Undo", on_press=lambda x: self.draw.undo()))
    toolbar.add_widget(Button(text="Save", on_press=lambda x: self.save_image()))

    self.add_widget(toolbar)

# ==========================
# TOGGLE DRAWING MODE
# ==========================
def toggle_draw(self, btn):
    self.draw.drawing_enabled = not self.draw.drawing_enabled
    btn.text = "Draw Off" if self.draw.drawing_enabled else "Draw On"

# ==========================
# SAVE MERGED IMAGE
# ==========================
def save_image(self):
    self.export_to_png("edited_graph.png")
    print("Saved as edited_graph.png")
class AnnotatorApp(App):
def build(self):
return EditorUI()

AnnotatorApp().run()